Acrylic plates have been widely used in edge light type surface light emitter devices, for example, light guide body units of liquid crystal televisions. However, from the viewpoints of rigidity, heat resistance and water resistance, replacement to glass plates has been studied.
When the glass plate is applied to the light guide body, light absorption of the inside of the glass plate in a visible light region (wavelength: 380 to 780 nm) cannot be negligible as an optical path length becomes longer by an increase in size of a screen, and a problem of a reduction in luminance or occurrence of in-plane luminance/color unevenness is assumed. In addition, it is also considered that even a small amount of foam defects in the inside of the glass plate largely deteriorate product properties.
Regardless of the above-mentioned application, a glass article having a high transmittance in the visible light region has been required to suppress both solarization and discoloration, in addition to the problem as described above.
Patent Documents 1 to 3 each disclose glass having a high transmittance in the visible light region.